Star pattern partial encryption

ABSTRACT

A selective encryption encoder consistent with certain embodiments of the invention has a packet identifier that identifies packets of a specified packet type, the specified packet type being defined by packets occurring in a star pattern approximately situated at an upper center of an image which contain intra-coded macroblocks. A packet duplicator duplicates the identified packets to produce first and second sets of the identified packets. The packets are sent to and from a primary encryption encoder to encrypt the first set of identified packets under a first encryption method. A secondary encrypter encrypts the second set of identified packets under a second encryption method.

CROSS REFERENCE TO RELATED DOCUMENTS

[0001] This application is a continuation in part of patent applicationsdocket number SNY-R4646.01 entitled “Critical Packet Partial Encryption”to Unger et al., Ser. No. 10/038,217; patent applications docket numberSNY-R4646.02 entitled “Time Division Partial Encryption” to Candelore etal., Ser. No. 10/038,032; docket number SNY-R4646.03 entitled“Elementary Stream Partial Encryption” to Candelore, Ser. No.10/037,914; docket number SNY-R4646.04 entitled “Partial Encryption andPID Mapping” to Unger et al., Ser. No. 10/037,499; and docket numberSNY-R4646.05 entitled “Decoding and Decrypting of Partially EncryptedInformation” to Unger et al., Ser. No. 10/037,498 all of which werefiled on Jan. 2, 2002 and are hereby incorporated by reference herein.

[0002] This application is also related to and claims priority benefitof U.S. Provisional patent application serial No. 60/372,901 filed Apr.16, 2002, docket number 50S5064 entitled “Method for PartiallyScrambling Content by Encryption of Intracoded Macroblock in the Centerof the TV Image” to Candelore, et al.; and U.S. Provisional patentapplication serial No. 60/355,326 filed Feb. 8, 2002 docket number50R4900, entitled “Analysis of Content Selection Methods”, to Candelore.These applications are also hereby incorporated by reference herein.

COPYRIGHT NOTICE

[0003] A portion of the disclosure of this patent document containsmaterial which is subject to copyright protection. The copyright ownerhas no objection to the facsimile reproduction of the patent document orthe patent disclosure, as it appears in the Patent and Trademark Officepatent file or records, but otherwise reserves all copyright rightswhatsoever.

FIELD OF THE INVENTION

[0004] This invention relates generally to the field of encryption. Moreparticularly, this invention relates to a dual encryption method andapparatus particularly useful for scrambling packetized video contentsuch as that provided by cable and satellite television systems.

BACKGROUND OF THE INVENTION

[0005] The above-referenced commonly owned patent applications describeinventions relating to various aspects of methods generally referred toherein as partial encryption or selective encryption. More particularly,systems are described therein wherein selected portions of a particularselection of digital content are encrypted using two (or more)encryption techniques while other portions of the content are leftunencrypted. By properly selecting the portions to be encrypted, thecontent can effectively be encrypted for use under multiple decryptionsystems without the necessity of encryption of the entire selection ofcontent. In some embodiments, only a few percent of data overhead isneeded to effectively encrypt the content using multiple encryptionsystems. This results in a cable or satellite system being able toutilize Set-top boxes or other implementations of conditional access(CA) receivers from multiple manufacturers in a single system—thusfreeing the cable or satellite company to competitively shop forproviders of Set-top boxes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The features of the invention believed to be novel are set forthwith particularity in the appended claims. The invention itself however,both as to organization and method of operation, together with objectsand advantages thereof, may be best understood by reference to thefollowing detailed description of the invention, which describes certainexemplary embodiments of the invention taken in conjunction with theaccompanying drawings in which:

[0007]FIG. 1 is a block diagram of an exemplary cable system head endconsistent with certain embodiments of the present invention.

[0008]FIG. 2 is an illustration of sample transport stream PSIconsistent with certain embodiments of the present invention.

[0009]FIG. 3 is a further illustration of sample transport stream PSIconsistent with certain embodiments of the present invention.

[0010]FIG. 4 is a block diagram of an illustrative control processor 100consistent with certain embodiments of the present invention.

[0011]FIG. 5 illustrates the slice structure of a frame of video dataconsistent with certain embodiments of the present invention.

[0012]FIG. 6 illustrates a star pattern of encrypted packets consistentwith certain embodiments of the present invention.

[0013]FIG. 7 illustrates a television Set-top box that decrypts anddecodes in a manner consistent with certain embodiments of the presentinvention.

[0014]FIG. 8 is a flow chart broadly illustrating an encryption processconsistent with embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0015] While this invention is susceptible of embodiment in manydifferent forms, there is shown in the drawings and will herein bedescribed in detail specific embodiments, with the understanding thatthe present disclosure is to be considered as an example of theprinciples of the invention and not intended to limit the invention tothe specific embodiments shown and described. In the description below,like reference numerals are used to describe the same, similar orcorresponding parts in the several views of the drawings.

[0016] The terms “scramble” and “encrypt” and variations thereof areused synonymously herein. Also, the term “television program” andsimilar terms can be interpreted in the normal conversational sense, aswell as a meaning wherein the term means any segment of AN content thatcan be displayed on a television set or similar monitor device. The term“video” is often used herein to embrace not only true visualinformation, but also in the conversational sense (e.g., “video taperecorder”) to embrace not only video signals but associated audio anddata. The term “legacy” as used herein refers to existing technologyused for existing cable and satellite systems. The exemplary embodimentsdisclosed herein are decoded by a television Set-Top Box (STB), but itis contemplated that such technology will soon be incorporated withintelevision receivers of all types whether housed in a separate enclosurealone or in conjunction with recording and/or playback equipment orConditional Access (CA) decryption module or within a television setitself. The present document generally uses the example of a “dualpartial encryption” embodiment, but those skilled in the art willrecognize that the present invention can be utilized to realize multiplepartial encryption without departing from the invention. Partialencryption and selective encryption are used synonymously herein.

[0017] Turning now to FIG. 1, a head end 100 of a cable televisionsystem suitable for use in practicing a dual encryption embodiment ofthe present invention is illustrated. Those skilled in the art willappreciate that the present invention could also be implemented usingmore than two encryptions systems without departing from the presentinvention. The illustrated head end 100 implements the dual partialencryption scenario of the present invention by adapting the operationof a conventional encryption encoder 104 (such as those provided byMotorola, Inc. and Scientific-Atlanta, Inc., and referred to herein asthe primary encryption encoder) with additional equipment.

[0018] Head end 100 receives scrambled content from one or moresuppliers, for example, using a satellite dish antenna 108 that feeds asatellite receiver 110. Satellite receiver 110 operates to demodulateand descramble the incoming content and supplies the content as a streamof clear (unencrypted) data to a selective encryption encoder 114. Theselective encryption encoder 114, according to certain embodiments, usestwo passes or two stages of operation, to encode the stream of data.Encoder 114 utilizes a secondary conditional access system (and thus asecond encryption method) in conjunction with the primary encryptionencoder 104 which operates using a primary conditional access system(and thus a primary encryption method). A user selection provided via auser interface on a control computer 118 configures the selectiveencryption encoder 114 to operate in conjunction with either a Motorolaor Scientific Atlanta cable network (or other cable or satellitenetwork).

[0019] It is assumed, for purposes of the present embodiment of theinvention, that the data from satellite receiver 110 is supplied as MPEG(Moving Pictures Expert Group) compliant packetized data. In the firststage of operation the data is passed through a Special PacketIdentifier (PID) 122. Special Packet Identifier 122 identifies specificprogramming that is to be dual partially encrypted according to thepresent invention. The Special Packet Identifier 122 signals the SpecialPacket Duplicator 126 to duplicate special packets. The PacketIdentifier (PID) Remapper 130, under control of the computer 118, toremap the PIDs of the elementary streams (ES) (i.e., audio, video, etc.)of the programming that shall remain clear and the duplicated packets tonew PID values. The payload of the elementary stream packets are notaltered in any way by Special Packet Identifier 122, Special PacketDuplicator 126, or PID remapper 1306. This is done so that the primaryencryption encoder 104 will not recognize the clear unencrypted contentas content that is to be encrypted.

[0020] The packets may be selected by the special packet identifier 122according to one of the selection criteria described in theabove-referenced applications or may use another selection criteria suchas those which will be described later herein. Once these packets areidentified in the packet identifier 122, packet duplicator 126 createstwo copies of the packet. The first copy is identified with the originalPID so that the primary encryption encoder 104 will recognize that it isto be encrypted. The second copy is identified with a new and unusedPID, called a “secondary PID” (or shadow PID) by the PID Remapper 122.This secondary PID will be used later by the selective encryptionencoder 114 to determine which packets are to be encrypted according tothe secondary encryption method. FIG. 2 illustrates an exemplary set oftransport PSI tables 136 after this remapping with a PAT 138 definingtwo programs (10 and 20) with respective PID values 0100 and 0200. Afirst PMT 140 defines a PID=0101 for the video elementary stream andPIDs 0102 and 0103 for two audio streams for program 10. Similarly, asecond PMT 142 defines a PID=0201 for the video elementary stream andPIDs 0202 and 0203 for two audio streams for program 20.

[0021] As previously noted, the two primary commercial providers ofcable head end encryption and modulation equipment are (at this writing)Motorola, Inc. and Scientific-Atlanta, Inc. While similar in operation,there are significant differences that should be discussed beforeproceeding since the present selective encryption encoder 114 isdesirably compatible with either system. In the case of Motorolaequipment, the Integrated Receiver Transcoder (IRT), an unmodulatedoutput is available and therefore there is no need to demodulate theoutput before returning a signal to the selective encryption encoder114, whereas no such unmodulated output is available in aScientific-Atlanta device. Also, in the case of currentScientific-Atlanta equipment, the QAM, the primary encryption encodercarries out a PID remapping function on received packets. Thus,provisions are made in the selective encryption encoder 114 to addressthis remapping.

[0022] In addition to the above processing, the Program SpecificInformation (PSI) is also modified to reflect this processing. Theoriginal, incoming Program Association Table (PAT) is appended withadditional Program Map Table (PMT) entries at a PMT inserter 134. Eachadded PMT entry contains the new, additional streams (remapped & shadowPIDs) created as part of the selective encryption (SE) encoding processfor a corresponding stream in a PMT of the incoming transport. These newPMT entries will mirror their corresponding original PMTs. The programnumbers will be automatically assigned by the selective encryptionencoder 114 based upon open, available program numbers as observed fromthe program number usage in the incoming stream. The selectiveencryption System 114 system displays the inserted program information(program numbers, etc) on the configuration user interface of controlcomputer 118 so that the Multiple System Operator (MSO, e.g., the cablesystem operator) can add these extra programs into the SystemInformation (SI) control system and instruct the system to carry theseprograms in the clear.

[0023] The modified transport PSI is illustrated as 144 in FIG. 3 withtwo additional temporary PMTs 146 and 148 appended to the tables oftransport PSI 136. The appended PMTs 146 and 148 are temporary. They areused for the primary encryption process and are removed in the secondpass of processing by the secondary encryption encoder. In accordancewith the MPEG standard, all entries in the temporary PMTs are markedwith stream type “user private” with an identifier of 0xF0. These PMTsdescribe the remapping of the PIDs for use in later recovery of theoriginal mapping of the PIDs in the case of a PID remapping in theScientific-Atlanta equipment. Of course, other identifiers could be usedwithout departing from the present invention.

[0024] In order to assure that the Scientific-Atlanta PID remappingissue is addressed, if the selective encryption encoder 114 isconfigured to operate with a Scientific-Atlanta system, the encoder addsa user private data descriptor to each elementary stream found in theoriginal PMTs in the incoming data transport stream (TS) per the formatbelow (of course, other formats may also be suitable): Syntax value # ofbits private_data_indicator_descriptor() {     descriptor_tag 0xF0 8    descriptor_length 0x04 8     private_data_indicator() {      orig_pid 0x???? 16       stream_type 0x?? 8       reserved 0xEF 8    } }

[0025] The selective encryption encoder 114 of the current embodimentalso adds a user private data descriptor to each elementary streamplaced in the temporary PMTs created as described above per the formatbelow: Syntax value # of bits private_data_indicator_descriptor() {    descriptor_tag 0xF0 8     descriptor_length 0x04 8    private_data_indicator() {       orig_pid 0x???? 16      stream_type 0x?? 8       reserved 0xFF 8     } }

[0026] The “???” in the tables above is the value of the “orig_pid”which is a variable while the “??” is a “stream_type” value. The datafield for “orig_pid” is a variable that contains the original incomingPID or in the case of remap or shadow PIDs, the original PID that thisstream was associated with. The data field “stream_type” is a variablethat describes the purpose of the stream based upon the chart below:Stream Type Value Legacy ES 0x00 Remapped ES 0x01 Shadow ES 0x02Reserved 0x03-0xFF

[0027] These descriptors will be used later to re-associate the legacyelementary streams, which are encrypted by the Scientific-Atlanta, Inc.primary encryption encoder 104, with the corresponding shadow andremapped clear streams after PID remapping in the Scientific-Atlanta,Inc. modulator prior to the second phase of processing of the SelectiveEncryption Encoder. Those skilled in the art will appreciate that theabove specific values should be considered exemplary and other specificvalues could be used without departing from the present invention.

[0028] In the case of a Motorola cable system being selected in theselective encryption encoder configuration GUI, the original PAT andPMTs can remain unmodified, providing the system does not remap PIDswithin the primary encryption encoder. The asterisks in FIG. 1 indicatefunctional blocks that are not used in a Motorola cable system.

[0029] The data stream from selective encryption encoder 114 is passedalong to the input of the primary encryption encoder 104 which firstcarries out a PID filtering process at 150 to identify packets that areto be encrypted. At 152, in the case of a Scientific-Atlanta device, aPID remapping may be carried out. The data are then passed along to anencrypter 154 that, based upon the PID of the packets encrypts certainpackets (in accord with the present invention, these packets are thespecial packets which are mapped by the packet duplicator 130 to theoriginal PID of the incoming data stream for the current program). Theremaining packets are unencrypted. The data then passes through a PSImodifier 156 that modifies the PSI data to reflect changes made at thePID remapper. The data stream is then modulated by a quadratureamplitude modulation (QAM) modulator 158 (in the case of theScientific-Atlanta device) and passed to the output thereof. Thismodulated signal is then demodulated by a QAM demodulator 160. Theoutput of the demodulator 160 is directed back to the selectiveencryption encoder 114 to a PSI parser 164.

[0030] The second phase of processing of the transport stream forselective encryption is to recover the stream after the legacyencryption process is carried out in the primary encryption encoder 104.The incoming Program Specific Information (PSI) is parsed at 164 todetermine the PIDs of the individual elementary streams and theirfunction for each program, based upon the descriptors attached in thefirst phase of processing. This allows for the possibility of PIDremapping, as seen in Scientific-Atlanta primary encryption encoders.The elementary streams described in the original program PMTs arelocated at PSI parser 164 where these streams have been reduced to justthe selected packets of interest and encrypted in the legacy CA systemformat in accord with the primary encryption method at encoder 104. Theelementary streams in the temporary programs appended to the originalPSI are also recovered at elementary stream concatenator 168. Thepackets in the legacy streams are appended to the remapped content,which is again remapped back to the PID of the legacy streams,completing the partial, selective encryption of the original elementarystreams.

[0031] The temporary PMTs and the associated PAT entries are discardedand removed from the PSI. The user private data descriptors added in thefirst phase of processing are also removed from the remaining originalprogram PMTs in the PSI. For a Motorola system, no PMT or PATreprocessing is required and only the final secondary encryption of thetransport stream occurs.

[0032] During the second phase of processing, the SE encoder 114 createsa shadow PSI structure that parallels the original MPEG PSI, forexample, having at PAT origin at PID 0x0000. The shadow PAT will belocated at a PID specified in the SE encoder configuration as indicatedby the MSO from the user interface. The shadow PMT PIDs will beautomatically assigned by the SE encoder 114 dynamically, based uponopen, available PID locations as observed from PID usage of the incomingstream. The PMTs are duplicates of the original PMTs, but also have CAdescriptors added to the entire PMT or to the elementary streamsreferenced within to indicate the standard CA parameters and optionally,shadow PID and the intended operation upon the associated elementarystream. The CA descriptor can appear in the descriptor1( ) ordescriptor2( ) loops of the shadow PMT. If found in descriptor1( ), theCA_PID called out in the CA descriptor contains the non-legacy ECM PIDwhich would apply to an entire program. Alternatively, the ECM PID maybe sent in descriptor2( ). The CA descriptor should not reference theselective encryption elementary PID in the descriptor1( ) area. CA PIDDefinition Secondary CA private data Value ECM PID 0x00 Replacement PID0x01 Insertion PID 0x02 ECM PID undefined (default)

[0033] This shadow PSI insertion occurs regardless of whether theselective encryption operation is for a Motorola or Scientific Atlantacable network. The elementary streams containing the duplicated packetsof interest that were also assigned to the temporary PMTs are encryptedduring this second phase of operation at secondary packet encrypter inthe secondary CA format based upon the configuration data of the CAsystem attached using the DVB (Digital Video Broadcasting) Simulcrypt™standard.

[0034] The data stream including the clear data, primary encrypted data,secondary encrypted data and other information are then passed to a PSImodifier 176 that modifies the transport PSI information by deletion ofthe temporary PMT tables and incorporation of remapping as describedabove. The output of the PSI modifier 176 is modulated at a QAMmodulator 180 and delivered to the cable plant 184 for distribution tothe cable system's customers.

[0035] The control processor 100 may be a personal computer based devicethat is used to control the selective encryption encoder as describedherein. An exemplary personal computer based controller 100 is depictedin FIG. 4. Control processor 100 has a central processor unit (CPU) 210with an associated bus 214 used to connect the central processor unit210 to Random Access Memory 218 and Non-Volatile Memory 222 in a knownmanner. An output mechanism at 226, such as a display and possiblyprinter, is provided in order to display and/or print output for thecomputer user as well as to provide a user interface such as a GraphicalUser Interface (GUI). Similarly, input devices such as keyboard andmouse 230 may be provided for the input of information by the user atthe MSO. Computer 100 also may have disc storage 234 for storing largeamounts of information including, but not limited to, program files anddata files. Computer system 100 also has an interface 238 for connectionto the selective encryption encoder 114. Disc storage 234 can store anynumber of encryption methods that can be downloaded as desired by theMSO to vary the encryption on a regular basis to thwart hackers.Moreover, the encryption methods can be varied according to othercriteria such as availability of bandwidth and required level ofsecurity.

[0036] The partial encryption process described above utilizes anysuitable conditional access encryption method at encrypters 154 and 174.However, these encryption techniques are selectively applied to the datastream using a technique such as those described below or in theabove-referenced patent applications. In general, but without the intentto be limiting, the selective encryption process utilizes intelligentselection of information to encrypt so that the entire program does nothave to undergo dual encryption. By appropriate selection of appropriatedata to encrypt, the program material can be effectively scrambled andhidden from those who desire to hack into the system and illegallyrecover commercial content without paying. The MPEG (or similar format)data that are used to represent the audio and video data does so using ahigh degree of reliance on the redundancy of information from frame toframe. Certain data can be transmitted as “anchor” data representingchrominance and luminance data. That data is then often simply movedabout the screen to generate subsequent frames by sending motion vectorsthat describe the movement of the block. Changes in the chrominance andluminance data are also encoded as changes rather than a recoding ofabsolute anchor data.

[0037] The MPEG specification defines a slice as “ . . . a series of anarbitrary number of consecutive macroblocks. The first and lastmacroblocks of a slice shall not be skipped macroblocks. Every sliceshall contain at least one macroblock. Slices shall not overlap. Theposition of slices may change from picture to picture. The first andlast macroblock of a slice shall be in the same horizontal row ofmacroblocks. Slices shall occur in the bitstream in the order in whichthey are encountered, starting at the upper-left of the picture andproceeding by raster-scan order from left to right and top to bottom . .. .”

[0038] By way of example, to represent an entire frame of NTSCinformation, the frame (picture) is divided into 30 slices (but ingeneral j slices may make up a full frame). Each slice contains 33variable length macroblocks (but in general can include k variablelength macroblocks) of information representing a 16×16 pixel region ofthe image. This is illustrated as frame 250 of FIG. 5 with each slicestarting with a slice header (SH1-SH30) and each slice having 33macroblocks (MB1-MB33). By appropriate selection of particular datarepresenting the frame, the image can be scrambled beyond recognition ina number of ways as will be described below. By variation of theselection criteria for selective encryption, hackers can be thwarted ona continuing basis. Moreover, the selection criteria can be changed toadapt to bandwidth requirements as well as need for security ofparticular content (or other criteria).

[0039] It is noted that the portion of the picture that generallycarries information of most interest to the viewer is approximately thecenter of the image. A suitable tradeoff between bandwidth andencryption security consistent with embodiments of the present inventioninvolves encryption of selected portions of the image which can bedeemed the “active region” of the image. This region is somewhatdifficult to define and is somewhat content dependent. But, generallyspeaking it is approximately an upper central area of the frame.According to one embodiment consistent with the present invention,macroblocks in this active region are encrypted while macroblocksextending somewhat radially from this central region are encrypted withless frequency.

[0040]FIG. 6 illustrates an embodiment of the invention in which slicesin a central area of the frame 270 are encrypted with a star pattern 274extending outward radially from the upper center of the frame. In thisembodiment, macroblocks having intracoded data are encrypted if theyfall within the shaded area of the star pattern 274. In one embodimentconsistent with the present invention, intracoded macroblocks areencrypted if, for standard definition, they fall within the definitionof the star pattern 274 given in the table below: SLICE ENCRYPTEDINTRA-CODED MACROBLOCKS 1-6 14-21  7-12 11-23 13-18  1-33 19-21 11-2322-30 14-21

[0041] For an interlaced high definition video image, the video frame ismade up of slices each carrying 120 macroblocks. For such an image, thetable below is one embodiment of how a star pattern can be realized:SLICE ENCRYPTED INTRA-CODED MACROBLOCKS  1-12 50-77 13-27 40-84 28-41 1-120 42-48 40-84 49-60 50-77

[0042] For a progressive high definition video image, the video frame ismade up of 45 slices each carrying 80 macroblocks. For such an image,the table below is one embodiment of how a star pattern can be realized:SLICE ENCRYPTED INTRA-CODED MACROBLOCKS 1-9 34-51 10-18 26-56 19-27 1-80 28-31 26-56 32-45 34-51

[0043] Similar star patterns can be devised for any other video framedefinition without departing from the invention. Moreover, variations ofstar patterns in which varying numbers of rays extend in variousdirections from a central or upper central area of the frame at variousangles can be devised without departing from the invention.

[0044] As defined above, star pattern 274 is slightly asymmetrical witha weighting of the central area of the star being situated approximatelyone slice above center. Star pattern 274 has rays or points of the starextending vertically and horizontally across the entire frame. The starpattern 274 further has rays defined by the corners of the centralregion that extend diagonally outward from the center.

[0045] Those skilled in the art will understand that the abovedefinition of the star pattern 274 is but one such definition within thescope of the invention. The number of intracoded macroblocks per sliceor number of slices in a particular section of the star can be variedwithout departing from the present invention. Moreover, other star-likepatterns can be used in place of the squared off pattern 274 depicted inFIG. 6, or the star pattern can be shifted within the image withoutdeparting from the invention. Such variations are considered equivalentand within the scope of the present invention so long as a central oractive region of the image is encrypted with lower levels of encryptionradiating outward from the active region.

[0046] Thus, in accordance with one embodiment consistent with thepresent invention, an packet containing an intra-coded macroblock in astar pattern such as that defined in the above table will be encryptedwhile the remaining packets will either be selectively encryptedaccording to another criterion, or transmitted in the clear. Dependingupon the actual definition of the active region, the overhead requiredfor dual encryption of a star pattern will vary. In other embodiments,all macroblocks within this star pattern can be encrypted.

[0047] In preferred embodiments, intra-coded macroblocks (or packetscontaining such macroblocks) are encrypted rather than all macroblockswithin the star pattern, but this is not to be considered limiting.Intra-coded macroblocks contain anchor data such as absolute chrominanceand/or luminance data used by inter-coded macroblocks to derive animage. By encryption of these intra-coded macroblocks, the inter-codedmacroblocks are robbed of their point of reference and the image issubstantially disrupted.

[0048] In this encryption technique, the active portion of the screen isdeemed to be the area of most interest to the viewer. Although someintelligible video information may be present outside the star pattern,the encrypted star pattern is likely to produce a major annoyance to anunauthorized viewer. Moreover, the packetizing of the star pattern willlikely result in additional data being encrypted. By encrypting theintra-coded blocks, inter-coded data will be deprived of a reference andthus produce the desired scrambling effect. This technique can be usedalone or with other selective encryption techniques to produce lowoverhead encryption. Additionally, the present invention is suitable notonly for multiple encryption scenarios, but also for single encryptionof a video signal. In accordance with certain embodiments of the presentinvention, any technique that detects macroblocks containing intra-codeddata within the star pattern can be used as a selection criterion forselecting data or data packets for encryption.

[0049] Multiple combinations of the encryption techniques are possibleto produce encryption that has varying bandwidth requirements, varyinglevels of security and varying complexity. For example, the above starpattern could be encrypted along with packets containing slice headers,or the above star pattern could be encrypted along with packetscontaining slice headers and the first macroblock following each sliceheader.

[0050] Numerous other combinations of the above encryption techniques aswell as those described in the above-referenced patent applications andother partial encryption techniques can be combined to produce a richpallette of encryption techniques from which to select. In accordancewith certain embodiments of the present invention, a selection ofpackets to encrypt can be made by the control computer 118 in order tobalance encryption security with bandwidth and in order to shift theencryption technique from time to time to thwart hackers.

[0051] An authorized set-top box such as 300 illustrated in FIG. 7operating under the secondary CA system decrypts and decodes theincoming program by recognizing both primary and secondary PIDsassociated with a single program. The multiplexed video data streamcontaining both PIDs is directed to a demultiplexer 304. When a programis received that contains encrypted content that was encrypted by any ofthe above techniques, the demultiplexer directs encrypted packetscontaining encrypted content and secondary PIDS to a secondary CAdecrypter 308. These packets are then decrypted at 308 and passed to aPID remapper 312. As illustrated, the PID remapper 312 receives packetsthat are unencrypted and bear the primary PID as well as the decryptedpackets having the secondary PID. The PID remapper 312 combines thedecrypted packets from decrypter 308 with the unencrypted packets havingthe primary PID to produce an unencrypted data stream representing thedesired program. PID remapping is used to change either the primary orsecondary PID or both to a single PID. This unencrypted data stream canthen be decoded normally by decoder 316. Some or all of the componentsdepicted in FIG. 7 can be implemented as program code running on aprogrammed processor running code stored on an electronic storagemedium.

[0052]FIG. 8 is a flow chart 400 that broadly illustrates the encryptionprocess consistent with certain embodiments of the present inventionstarting at 404. At 408 the packet type that is to be encrypted isspecified. In accordance with certain embodiments consistent with thepresent invention, the selected packet type may be packets representinga star pattern in the video frame. Packets are then examined at 412 toidentify packets of the specified type. At 416, the identified packetsare duplicated and at 420 one set of these packets is encrypted under afirst encryption method. The other set of identified packets isencrypted at 424 under a second encryption method. The originallyidentified packets are then replaced in the data stream with the twosets of encrypted packets at 430 and the process ends at 436.

[0053] While the above embodiments describe encryption of packetscontaining the selected data type, it is also possible to encrypt theraw data prior to packetizing without departing from this invention andsuch encryption is considered equivalent thereto.

[0054] Those skilled in the art will recognize that the presentinvention has been described in terms of exemplary embodiments basedupon use of a programmed processor (e.g., processor 118, processorsimplementing any or all of the elements of 114 or implementing any orall of the elements of 300). However, the invention should not be solimited, since the present invention could be implemented using hardwarecomponent equivalents such as special purpose hardware and/or dedicatedprocessors which are equivalents to the invention as described andclaimed. Similarly, general purpose computers, microprocessor basedcomputers, micro-controllers, optical computers, analog computers,dedicated processors and/or dedicated hard wired logic may be used toconstruct alternative equivalent embodiments of the present invention.

[0055] Those skilled in the art will appreciate that the program stepsand associated data used to implement the embodiments described abovecan be implemented using disc storage as well as other forms of storagesuch as for example Read Only Memory (ROM) devices, Random Access Memory(RAM) devices; optical storage elements, magnetic storage elements,magneto-optical storage elements, flash memory, core memory and/or otherequivalent storage technologies without departing from the presentinvention. Such alternative storage devices should be consideredequivalents.

[0056] The present invention, as described in embodiments herein, isimplemented using a programmed processor executing programminginstructions that are broadly described above form that can be stored onany suitable electronic storage medium or transmitted over any suitableelectronic communication medium or otherwise be present in any computerreadable or propagation medium. However, those skilled in the art willappreciate that the processes described above can be implemented in anynumber of variations and in many suitable programming languages withoutdeparting from the present invention. For example, the order of certainoperations carried out can often be varied, additional operations can beadded or operations can be deleted without departing from the invention.Error trapping can be added and/or enhanced and variations can be madein user interface and information presentation without departing fromthe present invention. Such variations are contemplated and consideredequivalent.

[0057] Software code and/or data embodying certain aspects of thepresent invention may be present in any computer readable medium,transmission medium, storage medium or propagation medium including, butnot limited to, electronic storage devices such as those describedabove, as well as carrier waves, electronic signals, data structures(e.g., trees, linked lists, tables, packets, frames, etc.) opticalsignals, propagated signals, broadcast signals, transmission media(e.g., circuit connection, cable, twisted pair, fiber optic cables,waveguides, antennas, etc.) and other media that stores, carries orpasses the code and/or data. Such media may either store the softwarecode and/or data or serve to transport the code and/or data from onelocation to another. In the present exemplary embodiments, MPEGcompliant packets, slices, tables and other data structures are used,but this should not be considered limiting since other data structurescan similarly be used without departing from the present invention.

[0058] While the invention has been described in conjunction withspecific embodiments, it is evident that many alternatives,modifications, permutations and variations will become apparent to thoseskilled in the art in light of the foregoing description. Accordingly,it is intended that the present invention embrace all such alternatives,modifications and variations as fall within the scope of the appendedclaims.

What is claimed is:
 1. A method of partially dual encrypting a digitalvideo signal, comprising: examining unencrypted packets of data in thedigital video signal to identify a specified packet type, the specifiedpacket type comprising packets occurring in a star pattern approximatelysituated at approximately a center of an image; encrypting packetsidentified as being of the specified packet type using a firstencryption method to produce first encrypted packets; encrypting thepackets identified as being of the specified packet type using a secondencryption method to produce second encrypted packets; and replacing theunencrypted packets of the specified packet type with the firstencrypted packets and the second encrypted packets in the digital videosignal to produce a partially dual encrypted video signal.
 2. The methodaccording to claim 1, wherein the specified packet type furthercomprises packets containing an intra-coded macroblock within the starpattern.
 3. The method according to claim 2, wherein a video framecomprises 30 slices each having 33 macroblocks, and wherein the starpattern is defined by: macroblocks 14-21 in slices 1-6 and 22-30,macroblocks 11-23 of slices 7-12 and 19-21 and macroblocks 1-33 ofslices 13-18.
 4. The method according to claim 2, wherein a video framecomprises 45 slices each having 80 macroblocks, and wherein the starpattern is defined by: macroblocks 34-51 in slices 1-9 and 32-45,macroblocks 26-56 of slices 10-18 and 28-31 and macroblocks 1-80 ofslices 19-27.
 5. The method according to claim 2, wherein a video framecomprises 68 slices each having 120 macroblocks, and wherein the starpattern is defined by: macroblocks 50-77 in slices 1-12 and 49-60,macroblocks 40-84 of slices 13-27 and 42-48 and macroblocks 1-120 ofslices 28-41.
 6. The method according to claim 1, wherein a video framecomprises 30 slices each having 33 macroblocks, and wherein the starpattern is defined by: macroblocks 14-21 in slices 1-6 and 22-30,macroblocks 11-23 of slices 7-12 and 19-21 and macroblocks 1-33 ofslices 13-18.
 7. The method according to claim 1, wherein a video framecomprises 68 slices each having 120 macroblocks, and wherein the starpattern is defined by: macroblocks 50-77 in slices 1-12 and 49-60,macroblocks 40-84 of slices 13-27 and 42-48 and macroblocks 1-120 ofslices 28-41.
 8. The method according to claim 1, wherein a video framecomprises 45 slices each having 80 macroblocks, and wherein the starpattern is defined by: macroblocks 34-51 in slices 1-9 and 32-45,macroblocks 26-56 of slices 10-18 and 28-31 and macroblocks 1-80 ofslices 19-27.
 9. The method according to claim 1, wherein the starpattern is centered above a true center of the image.
 10. The methodaccording to claim 1, wherein the star pattern has rays extendinghorizontally across a full width of the image.
 11. The method accordingto claim 1, wherein the star pattern has rays extending verticallyacross a full height of the image.
 12. The method according to claim 1,wherein the star pattern has a rectangular central region centeredapproximately one slice above a center of the image.
 13. A computerreadable medium storing instructions which, when executed on aprogrammed processor, carry out the method of encrypting a digital videosignal according to claim
 1. 14. The computer readable medium of claim13, wherein the medium comprises one of an electronic storage medium anda carrier wave.
 15. An electronic transmission medium carrying anencrypted digital video signal encrypted by the method according toclaim
 1. 16. A selective encryption encoder, comprising: a packetidentifier that identifies packets of a specified packet type, thespecified packet type comprising packets occurring in a star patternapproximately situated at a center of an image; a packet duplicator thatduplicates the identified packets to produce first and second sets ofthe identified packets; means for sending and receiving packets to andfrom a primary encryption encoder to encrypt the first set of identifiedpackets under a first encryption method; a secondary encrypter forencrypting the second set of identified packets under a secondencryption method.
 17. The selective encryption encoder according toclaim 16, wherein wherein the specified packet type further comprisespackets containing an intra-coded macroblock within the star pattern.18. The selective encryption encoder according to claim 17, wherein avideo frame comprises 30 slices each having 33 macroblocks, and whereinthe star pattern is defined by: macroblocks 14-21 in slices 1-6 and22-30, macroblocks 11-23 of slices 7-12 and 19-21 and macroblocks 1-33of slices 13-18.
 19. The selective encryption encoder according to claim17, wherein a video frame comprises 45 slices each having 80macroblocks, and wherein the star pattern is defined by: macroblocks34-51 in slices 1-9 and 32-45, macroblocks 26-56 of slices 10-18 and28-31 and macroblocks 1-80 of slices 19-27.
 20. The selective encryptionencoder according to claim 17, wherein a video frame comprises 68 sliceseach having 120 macroblocks, and wherein the star pattern is defined by:macroblocks 50-77 in slices 1-12 and 49-60, macroblocks 40-84 of slices13-27 and 42-48 and macroblocks 1-120 of slices 28-41.
 21. The selectiveencryption encoder according to claim 16, wherein a video framecomprises 30 slices each having 33 macroblocks, and wherein the starpattern is defined by: macroblocks 14-21 in slices 1-6 and 22-30,macroblocks 11-23 of slices 7-12 and 19-21 and macroblocks 1-33 ofslices 13-18.
 22. The selective encryption encoder according to claim16, wherein a video frame comprises 68 slices each having 120macroblocks, and wherein the star pattern is defined by: macroblocks50-77 in slices 1-12 and 49-60, macroblocks 40-84 of slices 13-27 and42-48 and macroblocks 1-120 of slices 28-41.
 23. The selectiveencryption encoder according to claim 16, wherein a video framecomprises 45 slices each having 80 macroblocks, and wherein the starpattern is defined by: macroblocks 34-51 in slices 1-9 and 32-45,macroblocks 26-56 of slices 10-18 and 28-31 and macroblocks 1-80 ofslices 19-27.
 24. The selective encryption encoder according to claim16, wherein the star pattern is centered above a true center of theimage.
 25. The selective encryption encoder according to claim 16,wherein the star pattern has rays extending horizontally across a fullwidth of the image.
 26. The selective encryption encoder according toclaim 16, wherein the star pattern has rays extending vertically acrossa full height of the image.
 27. The selective encryption encoderaccording to claim 16, wherein the star pattern has a rectangularcentral region centered approximately one slice above a center of theimage.
 28. A method of partially encrypting a digital video signal,comprising: examining unencrypted packets of data in the digital videosignal to identify a specified packet type, the specified packet typecomprising packets occurring in a star pattern; encrypting packetsidentified as being of the specified packet type using a firstencryption method to produce first encrypted packets; and replacing theunencrypted packets of the specified packet type with the firstencrypted packets in the digital video signal to produce a partiallyencrypted video signal.
 29. The method according to claim 28, furthercomprising encrypting the packets identified as being of the specifiedpacket type using a second encryption method to produce second encryptedpackets; and inserting the second encrypted packets into the digitalvideo signal to produce a dual partially encrypted video signal.
 30. Themethod according to claim 29, wherein the specified packet type furthercomprises packets containing an intra-coded macroblock within the starpattern.
 31. The method according to claim 28, wherein a video framecomprises 30 slices each having 33 macroblocks, and wherein the starpattern is defined by: macroblocks 14-21 in slices 1-6 and 22-30,macroblocks 11-23 of slices 7-12 and 19-21 and macroblocks 1-33 ofslices 13-18.
 32. The method according to claim 28, wherein a videoframe comprises 45 slices each having 80 macroblocks, and wherein thestar pattern is defined by: macroblocks 34-51 in slices 1-9 and 32-45,macroblocks 26-56 of slices 10-18 and 28-31 and macroblocks 1-80 ofslices 19-27.
 33. The method according to claim 28, wherein a videoframe comprises 68 slices each having 120 macroblocks, and wherein thestar pattern is defined by: macroblocks 50-77 in slices 1-12 and 49-60,macroblocks 40-84 of slices 13-27 and 42-48 and macroblocks 1-120 ofslices 28-41.
 34. The method according to claim 28, wherein the starpattern is centered above a true center of the image.
 35. The methodaccording to claim 28, wherein the star pattern has rays extendinghorizontally across a full width of the image.
 36. The method accordingto claim 28, wherein the star pattern has rays extending verticallyacross a full height of the image.
 37. The method according to claim 28,wherein the star pattern has a rectangular central region centeredapproximately one slice above a center of the image.
 38. A computerreadable medium storing instructions which, when executed on aprogrammed processor, carry out the method of encrypting a digital videosignal according to claim
 28. 39. The computer readable medium of claim38, wherein the medium comprises one of an electronic storage medium anda carrier wave.
 40. An electronic transmission medium carrying anencrypted digital video signal encrypted by the method according toclaim
 28. 41. A method of partially encrypting a digital video signal,comprising: examining unencrypted packets of data in the digital videosignal to identify a specified packet type, the specified packet typecomprising packets occurring in a star pattern approximately situated atan upper center of an image, and containing an intra-coded macroblock,the star pattern being centered above a true center of the image andhaving rays extending horizontally and vertically across a full widthand height of the image respectively, the star pattern further having arectangular central portion centered approximately one slice above acenter of the image; encrypting packets identified as being of thespecified packet type using a first encryption method to produce firstencrypted packets; and replacing the unencrypted packets of thespecified packet type with the first encrypted packets in the digitalvideo signal to produce a partially encrypted video signal.
 42. Themethod according to claim 41, wherein a video frame comprises 30 sliceseach having 33 macroblocks, and wherein the star pattern is defined by:macroblocks 14-21 in slices 1-6 and 22-30, macroblocks 11-23 of slices7-12 and 19-21 and macroblocks 1-33 of slices 13-18.
 43. The methodaccording to claim 41, wherein a video frame comprises 45 slices eachhaving 80 macroblocks, and wherein the star pattern is defined by:macroblocks 34-51 in slices 1-9 and 32-45, macroblocks 26-56 of slices10-18 and 28-31 and macroblocks 1-80 of slices 19-27.
 44. The methodaccording to claim 41, wherein a video frame comprises 68 slices eachhaving 120 macroblocks, and wherein the star pattern is defined by:macroblocks 50-77 in slices 1-12 and 49-60, macroblocks 40-84 of slices13-27 and 42-48 and macroblocks 1-120 of slices 28-41.
 45. A computerreadable medium storing instructions which, when executed on aprogrammed processor, carry out the method of encrypting a digital videosignal according to claim
 41. 46. The computer readable medium of claim45, wherein the medium comprises one of an electronic storage medium anda carrier wave.
 47. An electronic transmission medium carrying anencrypted digital video signal encrypted by the method according toclaim
 41. 48. A television set-top box, comprising: a receiver receivinga digital television signal comprising: a plurality of unencryptedpackets; and a plurality of encrypted packets, wherein the encryptedpackets are of at least one selected packet type and the at least oneselected packet type comprises packets occurring in a star patternapproximately situated at an upper center of an image; a decrypter thatdecrypts the encrypted packets; and a decoder that decodes theunencrypted packets and the decrypted packets to produce a signalsuitable for play on a television set.
 49. The television set-top boxaccording to claim 48, wherein wherein the specified packet type furthercomprises packets containing an intra-coded macroblock within the starpattern.
 50. The television set-top box according to claim 48, wherein avideo frame comprises 30 slices each having 33 macroblocks, and whereinthe star pattern is defined by: macroblocks 14-21 in slices 1-6 and22-30, macroblocks 11-23 of slices 7-12 and 19-21 and macroblocks 1-33of slices 13-18.
 51. The television set-top box according to claim 48,wherein a video frame comprises 45 slices each having 80 macroblocks,and wherein the star pattern is defined by: macroblocks 34-51 in slices1-9 and 32-45, macroblocks 26-56 of slices 10-18 and 28-31 andmacroblocks 1-80 of slices 19-27.
 51. The television set-top boxaccording to claim 48, wherein a video frame comprises 68 slices eachhaving 120 macroblocks, and wherein the star pattern is defined by:macroblocks 50-77 in slices 1-12 and 49-60, macroblocks 40-84 of slices13-27 and 42-48 and macroblocks 1-120 of slices 28-41.
 52. Thetelevision set-top box according to claim 48, wherein the star patternis centered above a true center of the image.
 53. The television set-topbox according to claim 48 wherein the star pattern has rays extendinghorizontally across a full width of the image.
 54. The televisionset-top box according to claim 48, wherein the star pattern has raysextending vertically across a full height of the image.
 55. Thetelevision set-top box according to claim 48, wherein the star patternhas a rectangular central region centered approximately one slice abovea center of the image.
 56. A selective encryption decoder, fordecrypting and decoding a selectively encrypted digital video signal,comprising: a demultiplexer that receives packets of digital video,certain of the packets being unencrypted and certain of the packetsbeing encrypted, wherein certain of the encrypted packets carry dataarranged in a star pattern within a video frame; the unencrypted packetshaving a first packet identifier (PID) and the encrypted packets havinga second packet identifier (PID); a decrypter receiving the encryptedpackets having the second PID and decrypting the encrypted packets usinga first encryption method to produce decrypted packets; a PID remapperthat changes at least one of the first and second PIDs so that theunencrypted packets and the decrypted packets have the same PID; and adecoder that decodes the unencrypted and decrypted packets to produce adecoded video signal.
 57. The selective encryption decoder according toclaim 56, wherein wherein the specified packet type further comprisespackets containing an intra-coded macroblock within the star pattern.58. The selective encryption decoder according to claim 56, wherein avideo frame comprises 30 slices each having 33 macroblocks, and whereinthe star pattern is defined by: macroblocks 14-21 in slices 1-6 and22-30, macroblocks 11-23 of slices 7-12 and 19-21 and macroblocks 1-33of slices 13-18.
 59. The selective encryption decoder according to claim56, wherein a video frame comprises 45 slices each having 80macroblocks, and wherein the star pattern is defined by: macroblocks34-51 in slices 1-9 and 32-45, macroblocks 26-56 of slices 10-18 and28-31 and macroblocks 1-80 of slices 19-27.
 60. The selective encryptiondecoder according to claim 56, wherein a video frame comprises 68 sliceseach having 120 macroblocks, and wherein the star pattern is defined by:macroblocks 50-77 in slices 1-12 and 49-60, macroblocks 40-84 of slices13-27 and 42-48 and macroblocks 1-120 of slices 28-41.
 61. The selectiveencryption decoder according to claim 56, wherein the star pattern iscentered above a true center of the image.
 62. The selective encryptiondecoder according to claim 56 wherein the star pattern has raysextending horizontally across a full width of the image.
 63. Theselective encryption decoder according to claim 56, wherein the starpattern has rays extending vertically across a full height of the image.64. The selective encryption decoder according to claim 56, wherein thestar pattern has a rectangular central region centered approximately oneslice above a center of the image.
 65. A method of decrypting anddecoding a selectively encrypted digital video signal, comprising:receiving packets of digital video, certain of the packets beingunencrypted and certain of the packets being encrypted, wherein certainof the encrypted packets carry data arranged in a star pattern within avideo frame; the unencrypted packets having a first packet identifier(PID) and the encrypted packets having a second packet identifier (PID);decrypting the encrypted packets having the second PID to producedecrypted packets; remapping at least one of the first and second PIDsso that the unencrypted packets and the decrypted packets have the samePID; and decoding the unencrypted and decrypted packets to produce adecoded video signal.
 66. The method according to claim 65, wherein thespecified packet type further comprises packets containing anintra-coded macroblock within the star pattern.
 67. The method accordingto claim 65, wherein a video frame comprises 30 slices each having 33macroblocks, and wherein the star pattern is defined by: macroblocks14-21 in slices 1-6 and 22-30, macroblocks 11-23 of slices 7-12 and19-21 and macroblocks 1-33 of slices 13-18.
 68. The method according toclaim 65, wherein a video frame comprises 45 slices each having 80macroblocks, and wherein the star pattern is defined by: macroblocks34-51 in slices 1-9 and 32-45, macroblocks 26-56 of slices 10-18 and28-31 and macroblocks 1-80 of slices 19-27.
 69. The method according toclaim 65, wherein a video frame comprises 68 slices each having 120macroblocks, and wherein the star pattern is defined by: macroblocks50-77 in slices 1-12 and 49-60, macroblocks 40-84 of slices 13-27 and42-48 and macroblocks 1-120 of slices 28-41.
 70. The method according toclaim 65, wherein the star pattern is centered above a true center ofthe image.
 71. The method according to claim 65, wherein the starpattern has rays extending horizontally across a full width of theimage.
 72. The method according to claim 65, wherein the star patternhas rays extending vertically across a full height of the image.
 73. Themethod according to claim 65, wherein the star pattern has a rectangularcentral region centered approximately one slice above a center of theimage.
 74. A computer readable medium storing instructions which, whenexecuted on a programmed processor, carry out the method of encrypting adigital video signal according to claim
 65. 75. The computer readablemedium of claim 74, wherein the medium comprises one of an electronicstorage medium and a carrier wave.
 76. An electronic transmission mediumcarrying a digital video signal decoded and decrypted by the methodaccording to claim
 65. 77. A computer readable medium that carriesinstructions that when executes on a programmed processor to facilitateoperation of a video receiver device to decrypt and decode a selectivelyencoded digital video signal wherein the instructions comprise: a codesegment that controls a demultiplexer that receives packets of digitalvideo, certain of the packets being unencrypted and certain of thepackets being encrypted, wherein certain of the encrypted packets carrydata arranged in a star pattern within a video frame, the unencryptedpackets having a first packet identifier (PID) and the encrypted packetshaving a second packet identifier (PID); a code segment that controlsdecryption of the encrypted packets to produce decrypted packets; a codesegment that controls remapping at least one of the first and secondPIDs so that the unencrypted packets and the decrypted packets have thesame PID; and a code segment that controls decoding the unencrypted anddecrypted packets to produce a decoded video signal.
 78. The computerreadable medium of claim 77, wherein the medium comprises one of anelectronic storage medium and a carrier wave.
 79. The computer readablemedium according to claim 77, wherein the specified packet type furthercomprises packets containing an intra-coded macroblock within the starpattern.
 80. The computer readable medium according to claim 77, whereina video frame comprises 30 slices each having 33 macroblocks, andwherein the star pattern is defined by: macroblocks 14-21 in slices 1-6and 22-30, macroblocks 11-23 of slices 7-12 and 19-21 and macroblocks1-33 of slices 13-18.
 81. The computer readable medium according toclaim 77, wherein a video frame comprises 45 slices each having 80macroblocks, and wherein the star pattern is defined by: macroblocks34-51 in slices 1-9 and 32-45, macroblocks 26-56 of slices 10-18 and28-31 and macroblocks 1-80 of slices 19-27.
 82. The computer readablemedium according to claim 77, wherein a video frame comprises 68 sliceseach having 120 macroblocks, and wherein the star pattern is defined by:macroblocks 50-77 in slices 1-12 and 49-60, macroblocks 40-84 of slices13-27 and 42-48 and macroblocks 1-120 of slices 28-41.
 83. The computerreadable medium according to claim 77, wherein the star pattern iscentered above a true center of the image.
 84. The computer readablemedium according to claim 77, wherein the star pattern has raysextending horizontally across a full width of the image.
 85. Thecomputer readable medium according to claim 77, wherein the star patternhas rays extending vertically across a full height of the image.
 86. Thecomputer readable medium according to claim 77, wherein the star patternhas a rectangular central region centered approximately one slice abovea center of the image.
 87. A selectively encrypted digital video signalembodied in a carrier wave, comprising: a stream of packets of videodata, wherein the stream of packets when not encrypted represent asegment of video content; certain of the packets being unencrypted andcertain of the packets being encrypted, wherein certain of the encryptedpackets carry video data arranged in a star pattern within a videoframe; a first segment of code that identifies the unencrypted packetsby a first packet identifier (PID); and a second segment of code thatidentifies the encrypted packets by a second packet identifier (PID).88. The selectively encrypted digital video signal embodied in a carrierwave according to claim 87, wherein the specified packet type furthercomprises packets containing an intra-coded macroblock within the starpattern.
 89. The selectively encrypted digital video signal embodied ina carrier wave according to claim 87, wherein a video frame comprises 30slices each having 33 macroblocks, and wherein the star pattern isdefined by: macroblocks 14-21 in slices 1-6 and 22-30, macroblocks 11-23of slices 7-12 and 19-21 and macroblocks 1-33 of slices 13-18.
 90. Theselectively encrypted digital video signal embodied in a carrier waveaccording to claim 87, wherein a video frame comprises 45 slices eachhaving 80 macroblocks, and wherein the star pattern is defined by:macroblocks 34-51 in slices 1-9 and 32-45, macroblocks 26-56 of slices10-18 and 28-31 and macroblocks 1-80 of slices 19-27.
 91. Theselectively encrypted digital video signal embodied in a carrier waveaccording to claim 87, wherein a video frame comprises 68 slices eachhaving 120 macroblocks, and wherein the star pattern is defined by:macroblocks 50-77 in slices 1-12 and 49-60, macroblocks 40-84 of slices13-27 and 42-48 and macroblocks 1-120 of slices 28-41.
 92. Theselectively encrypted digital video signal embodied in a carrier waveaccording to claim 87, wherein the star pattern is centered above a truecenter of the image.
 93. The selectively encrypted digital video signalembodied in a carrier wave according to claim 87, wherein the starpattern has rays extending horizontally across a full width of theimage.
 94. The selectively encrypted digital video signal embodied in acarrier wave according to claim 87, wherein the star pattern has raysextending vertically across a full height of the image.
 95. Theselectively encrypted digital video signal embodied in a carrier waveaccording to claim 87, wherein the star pattern has a rectangularcentral region centered approximately one slice above a center of theimage.
 96. A selectively encrypted digital video signal embodied in acomputer readable medium, comprising: a sequence of packets of videodata, wherein the sequence of packets when not encrypted represent asegment of video content; wherein certain of the packets areunencrypted; wherein certain of the packets have been produced bydecrypting encrypted packets; wherein certain of the encrypted packetscarry data arranged in a star pattern within a video frame; and asegment of code that identifies the unencrypted packets by a firstpacket identifier (PID); and a segment of code that identifies theencrypted packets by a second packet identifier (PID).
 97. Theselectively encrypted digital video signal embodied in a computerreadable medium according to claim 96, wherein the specified packet typefurther comprises packets containing an intra-coded macroblock withinthe star pattern.
 98. The selectively encrypted digital video signalembodied in a computer readable medium according to claim 96, wherein avideo frame comprises 30 slices each having 33 macroblocks, and whereinthe star pattern is defined by: macroblocks 14-21 in slices 1-6 and22-30, macroblocks 11-23 of slices 7-12 and 19-21 and macroblocks 1-33of slices 13-18.
 99. The selectively encrypted digital video signalembodied in a computer readable medium according to claim 96, wherein avideo frame comprises 45 slices each having 80 macroblocks, and whereinthe star pattern is defined by: macroblocks 34-51 in slices 1-9 and32-45, macroblocks 26-56 of slices 10-18 and 28-31 and macroblocks 1-80of slices 19-27.
 100. The selectively encrypted digital video signalembodied in a computer readable medium according to claim 96, wherein avideo frame comprises 68 slices each having 120 macroblocks, and whereinthe star pattern is defined by: macroblocks 50-77 in slices 1-12 and49-60, macroblocks 40-84 of slices 13-27 and 42-48 and macroblocks 1-120of slices 28-41.
 101. The selectively encrypted digital video signalembodied in a computer readable medium according to claim 96, whereinthe star pattern is centered above a true center of the image.
 102. Theselectively encrypted digital video signal embodied in a computerreadable medium according to claim 96, wherein the star pattern has raysextending horizontally across a full width of the image.
 103. Theselectively encrypted digital video signal embodied in a computerreadable medium according to claim 96, wherein the star pattern has raysextending vertically across a full height of the image.
 104. Theselectively encrypted digital video signal embodied in a computerreadable medium according to claim 96, wherein the star pattern has arectangular central region centered approximately one slice above acenter of the image.
 105. The selectively encrypted digital video signalembodied in a computer readable medium according to claim 96, whereinthe medium comprises one of an electronic storage medium and a carrierwave.